---
title: TestCaseAgent
description: "Reference for the `agent` object used in Magnitude tests."
icon: "bot"
---

The `agent` object is your primary tool for interacting with the browser within a Magnitude test. It's an instance of the `TestCaseAgent` class.

`TestCaseAgent` extends [`BrowserAgent`](/reference/browser-agent) and includes all of its methods, such as `act()`, `nav()`, and `extract()`.

In addition to the inherited methods, `TestCaseAgent` provides the following methods for making assertions:

## `agent.check(description)`

Verifies that a certain condition holds true on the web page based on a natural language description. The AI evaluates the description against the current page state (DOM, visibility, text content).

<RequestExample>
```typescript Complete Test Case Example
import { test } from 'magnitude-test';

test('should create three todos', async (agent) => {
    await agent.act('create three todos');
    await agent.check('three todos exist');
});
```
</RequestExample>

<ParamField path="description" type="string" required>
  A natural language statement describing the expected condition or state to verify.
</ParamField>
